There were initial difficulties in casting, and the character changed from one intended to be "spooky" to one struggling to deal with all her previous personalities, having taken on the Dax symbiont without the usual preparation.

De Boer was not considered for the part until co-producer Hans Beimler suggested that she submit an audition tape, which resulted in her meeting the producers in Los Angeles and subsequently gaining the role.

"[7] The initial casting call required an actress with a "spooky" quality, but following the failure to find someone adequate, co-supervising producer René Echevarria suggested that the character instead should be someone who was unprepared to be joined with Dax and only did so because of an unexpected occurrence.

"[8] The producers also decided that they wanted a younger actress who felt vulnerable in order to offset the strength that Jadzia had grown into over the years.

[8] She was asked to submit an audition tape in which she played out a scene between Ezri and Quark, which she recorded, herself, in her hotel room,[9][10] and later admitted that she did not know what a Trill was at the time.

"[8] As part of her preparation for each day's filming, she had the Trill spots applied by makeup artist Mary Kay Morse, with Michael Westmore working on her detailing instead.

"[13] De Boer felt that the producers did a good job with involving Ezri over the course of the seventh season, but not to the extent that it detracted from the more established members of the main cast.

"[13] She praised specific episodes that evolved the character, such as "The Siege of AR-558" which required Ezri to draw upon Dax's past experiences, as otherwise she would have been completely out of her element.

De Boer also enjoyed "Prodigal Daughter" as the episode showed the change in Ezri from before she was joined with the Dax symbiont, and she thought that the events portrayed in "Field of Fire" were "fascinating".

[13] As she approached the end of Deep Space Nine, de Boer addressed the rumors of her joining Star Trek: Voyager, saying that "My first instinct would be to say no.

[16] Ezri Dax made her first appearance on the Star Trek: Deep Space Nine series in the premiere episode of season seven, "Image in the Sand".

Worf (Michael Dorn), Jadzia's widower, reacts poorly, and Garak (Andrew Robinson) begins to develop the symptoms of acute claustrophobia.

Together, Ezri and Garak work through his issues, resulting in her realising that she can remain on the station and Starfleet agreeing to her skipping her final periods of training and receiving a promotion from ensign to lieutenant (junior grade) based on the past experiences of the Dax symbiont.

[19] In "The Siege of AR-558", Ezri is forced to rely on her symbiont's past experiences after she and the other members of the Defiant crew end up fighting against the Jem'Hadar on the front lines.

[20] In "Prodigal Daughter", Ezri returns to her family home on the planet New Sydney, in the Sappora system, after Sisko asks her to investigate the disappearance of Chief Miles O'Brien (Colm Meaney).

There she finds that her family and their pergium mining business are involved with the Orion Syndicate, and discovers that her brother Norvo (Kevin Rahm) murdered the person that O'Brien was searching for.

[16] The Mirror Universe episode "The Emperor's New Cloak" showed an unjoined Ezri Tigan, who is in a relationship with both the alternative Kira Nerys (Nana Visitor) and Leeta (Chase Masterson).

However, Damar (Casey Biggs), the leader of the Cardassian Union is concerned at what the new alliance might bring and wants to side with the Federation; he releases Ezri and Worf and sets them free to take a message back to Deep Space Nine to seek aid.

[27] In the series finale, "What You Leave Behind", Ezri and Bashir reveal their feelings for one another, and later after the fall of Cardassia Prime and the surrender of the Dominion, they discuss their future together.

[28] In Pocket Books' non-canon DS9 Relaunch novels, Ezri remains on Deep Space Nine but moves from counseling to command, and received a promotion to Lieutenant to become executive officer of the USS Defiant.

[32] In the Star Trek: The Next Generation novel Takedown, the newly promoted Admiral William Riker is stationed aboard the Aventine alongside Captain Dax, and the ship is pursued by the Enterprise as he is leading a number of renegade starships in attacking Federation targets, later revealed to be the result of Riker being brainwashed by an alien race and choosing the Aventine as a subtle means of disrupting their plans by performing his assigned tasks faster than anticipated to give his old shipmates time to deduce his plans and stop them.

Jim Johnson-Smith, in American Science Fiction TV, uses an example of Ezri and Worf's concentration on their romantic relationship in the episode "'Til Death Do Us Part" instead of being more concerned with their capture by the Breen.

[37] Ezri was described as "an ill-conceived idea that never really took off and has left many DS9 fans angry that a show favourite (Jadzia Dax) isn't around any more" by the website Flickering Myth.

DVD Talk described "Prodigal Daughter" as "clearly an attempt to cram some back-story into Ezri to make up for the fact that she's a new character",[4] and "Field of Fire" as "utterly generic".

This had occurred during the fifth season of Star Trek: The Next Generation in the episode "The Outcast" where Commander William Riker (Jonathan Frakes) has a romantic liaison with a female member of an alien race that is typically non-gendered and whose society views identifying with a gender as deviant behavior.

Because of real world changes, such as further acceptance of same-sex couples and an increased number of homosexual characters on television, the negative response to the lesbian version of Ezri was not as heavy as those earlier story-lines.